--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/test/test-pipe-sendmsg.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,172 @@
+/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "uv.h"
+#include "task.h"
+
+
+#ifndef _WIN32
+
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+
+/* NOTE: size should be divisible by 2 */
+static uv_pipe_t incoming[4];
+static unsigned int incoming_count;
+static unsigned int close_called;
+
+
+static void set_nonblocking(uv_os_sock_t sock) {
+  int r;
+#ifdef _WIN32
+  unsigned long on = 1;
+  r = ioctlsocket(sock, FIONBIO, &on);
+  ASSERT_OK(r);
+#else
+  int flags = fcntl(sock, F_GETFL, 0);
+  ASSERT_GE(flags, 0);
+  r = fcntl(sock, F_SETFL, flags | O_NONBLOCK);
+  ASSERT_GE(r, 0);
+#endif
+}
+
+
+
+
+static void close_cb(uv_handle_t* handle) {
+  close_called++;
+}
+
+
+static void alloc_cb(uv_handle_t* handle, size_t size, uv_buf_t* buf) {
+  static char base[1];
+
+  buf->base = base;
+  buf->len = sizeof(base);
+}
+
+
+static void read_cb(uv_stream_t* handle,
+                    ssize_t nread,
+                    const uv_buf_t* buf) {
+  uv_pipe_t* p;
+  uv_pipe_t* inc;
+  uv_handle_type pending;
+  unsigned int i;
+
+  p = (uv_pipe_t*) handle;
+  ASSERT_GE(nread, 0);
+
+  while (uv_pipe_pending_count(p) != 0) {
+    pending = uv_pipe_pending_type(p);
+    ASSERT_EQ(pending, UV_NAMED_PIPE);
+
+    ASSERT_LT(incoming_count, ARRAY_SIZE(incoming));
+    inc = &incoming[incoming_count++];
+    ASSERT_OK(uv_pipe_init(p->loop, inc, 0));
+    ASSERT_OK(uv_accept(handle, (uv_stream_t*) inc));
+  }
+
+  if (incoming_count != ARRAY_SIZE(incoming))
+    return;
+
+  ASSERT_OK(uv_read_stop((uv_stream_t*) p));
+  uv_close((uv_handle_t*) p, close_cb);
+  for (i = 0; i < ARRAY_SIZE(incoming); i++)
+    uv_close((uv_handle_t*) &incoming[i], close_cb);
+}
+
+
+TEST_IMPL(pipe_sendmsg) {
+#if defined(NO_SEND_HANDLE_ON_PIPE)
+  RETURN_SKIP(NO_SEND_HANDLE_ON_PIPE);
+#endif
+  uv_pipe_t p;
+  int r;
+  int fds[2];
+  int send_fds[ARRAY_SIZE(incoming)];
+  struct msghdr msg;
+  char scratch[64];
+  struct cmsghdr *cmsg;
+  unsigned int i;
+  uv_buf_t buf;
+
+  ASSERT_OK(socketpair(AF_UNIX, SOCK_STREAM, 0, fds));
+  for (i = 0; i < ARRAY_SIZE(send_fds); i += 2)
+    ASSERT_OK(socketpair(AF_UNIX, SOCK_STREAM, 0, send_fds + i));
+  ASSERT_EQ(i, ARRAY_SIZE(send_fds));
+  ASSERT_OK(uv_pipe_init(uv_default_loop(), &p, 1));
+  ASSERT_OK(uv_pipe_open(&p, fds[1]));
+
+  buf = uv_buf_init("X", 1);
+  memset(&msg, 0, sizeof(msg));
+  msg.msg_iov = (struct iovec*) &buf;
+  msg.msg_iovlen = 1;
+  msg.msg_flags = 0;
+
+  msg.msg_control = (void*) scratch;
+  msg.msg_controllen = CMSG_LEN(sizeof(send_fds));
+  ASSERT_GE(sizeof(scratch), msg.msg_controllen);
+
+  cmsg = CMSG_FIRSTHDR(&msg);
+  cmsg->cmsg_level = SOL_SOCKET;
+  cmsg->cmsg_type = SCM_RIGHTS;
+  cmsg->cmsg_len = msg.msg_controllen;
+
+  /* silence aliasing warning */
+  {
+    void* pv = CMSG_DATA(cmsg);
+    int* pi = pv;
+    for (i = 0; i < ARRAY_SIZE(send_fds); i++)
+      pi[i] = send_fds[i];
+  }
+
+  set_nonblocking(fds[1]);
+  ASSERT_OK(uv_read_start((uv_stream_t*) &p, alloc_cb, read_cb));
+
+  do
+    r = sendmsg(fds[0], &msg, 0);
+  while (r == -1 && errno == EINTR);
+  ASSERT_EQ(1, r);
+
+  uv_run(uv_default_loop(), UV_RUN_DEFAULT);
+  ASSERT_EQ(ARRAY_SIZE(incoming), incoming_count);
+  ASSERT_EQ(ARRAY_SIZE(incoming) + 1, close_called);
+  close(fds[0]);
+
+  MAKE_VALGRIND_HAPPY(uv_default_loop());
+  return 0;
+}
+
+#else  /* !_WIN32 */
+
+TEST_IMPL(pipe_sendmsg) {
+  MAKE_VALGRIND_HAPPY(uv_default_loop());
+  return 0;
+}
+
+#endif  /* _WIN32 */